March 2001 doc IEEE 802 15 01026 r

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Proposal for Non-Collaborative BT and 802. 11 b MAC Mechanisms for Enhanced Coexistence Jie Liang Texas Instruments Incorporated 12500 TI Blvd. Dallas, Texas 75243 (ph) 214 -480 -4105 (email) liang@ti. com Submission 1 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Outline • Summary of our ACL proposal • Focus on updated proposal to improve the BT voice link quality while improving 802. 11 b throughput • Proposals for improving BT voice links: – Selecting HV 3 packet as default packet type for SCO link – Enhanced voice link: allow Master flexibility to search for best TX slots given delay requirement • Simulation results that confirm significant improvement in throughput for both BT and 802. 11 b Submission 2 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Summary of ACL Proposals • Adaptive packet type selection considering slot time, FEC, CRC based on channel condition and Qo. S: DM 1, DM 3, DM 5, DH 1, DH 3, DH 5, AUX 1 • Adaptive packet payload length selection: fragmentation • Adaptive link configuration: flow control, rate control Submission 3 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 SCO Link Coexistence Problems Submission 4 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 SCO Link Coexistence Problem and Scenarios • A serious problem that needs urgent solutions • Voice applications are among the most important applications for BT • Significant packet losses for BT SCO links under 802. 11 b interference • Significant throughput drop for 802. 11 b network • Scenarios • Separated > 10 feet: minor problem • Problem when <10 feet distance • Also dependent on 802. 11 b duty cycle Submission 5 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Key Ideas • HV 3 packet type is the most coexistence friendly compared with HV 1 and HV 2 packets • Allow the master to search for the best TX slots given a delay requirement Submission 6 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Voice Payload and SCO Packets • Qo. S requirement of voice payload: – PCM coding: 10 -4 (random errors) good quality is retained 10 -3 start to notice artifacts, but still acceptable – CVSD coding: 10 -3 good quality is retained 10 -2 start to notice artifacts, but still acceptable – Perceptible errors mostly come from collisions (really high BER or fail to decode the BT packet header) • HV 1 vs. HV 2 vs. HV 3 – Packet payload length: 80, 160, 240 bits (1. 25 ms, 2. 5 ms, 3. 75 ms) – Tsco = 2, 4, 6 – FEC 1/3, 2/3, none Submission 7 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 802. 11 b Channel Access Timing Tbf DIFS Busy Medium Idle Tcp Frame Exchange Sequences SIFS Back-off Window ACK New Frame SIF= 10 us DIF = 50 us a. Slot_time = 20 us Tbf = N x a. Slot Tf=PLCP Preamble + Header = 192 us Minimum Time Needed (no back-off and payload): Tm= DIFS+Tf+SIFS+Tf=50+192+10+192=444 us 500 bytes Payload (add back-off and Payload at 11 Mbps): T=16 xa. Slot+Tm+400=1164 us Note: needs about 2 BT Slot time for transmitting one average packet for 11 Mbps 802. 11 b (a block of time is needed by 802. 11 b) Submission 8 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Adaptive SCO Link Configuration Proposal: Use HV 3 packet as default (more co-existence friendly) HV 1 Traffic HV 3 Traffic • Leave more time for 802. 11 transmissions • Lack of FEC in HV 3 is not problem ü high tolerance of random BER ü FEC does not help during collision • Transmit less often – good for saving power Submission 9 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Enhanced Voice Link (1) • New SCO packet type – EV 3: – – no FEC 240 bits payload One EV 3 packet for every 6 slots (delay<3. 75 ms) Slave will only transmit when addressed by master • Only master needs to do the scheduling • Make sure only one pair of slots are used – CRC: could be another option, which accommodate applications that want data integrity on voice data • Why: – Flexible in traffic scheduling to avoid collisions (no fixed intervals) Submission 10 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Enhanced Voice Link (2) B B G G G G G HV 3 Traffic B B G G B G EV 3 Traffic • Enhanced Voice Link Setup: new EV 3 packet type, payload size: 240 bits • • Submission Npoll: <6 slots Adaptive selection of transmitting slots based on channel conditions Delay < 3. 75 ms 11 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Algorithm for Selecting TX Slots hop 0 1 2 3 4 5 score B 0 B G 3 G B 1 G Score(n) = 0, if hop(2*n) and hop(2*n+1) are both bad channels 1, if hop(2*n) is bad and hop(2*n+1) is good 2, if hop(2*n) is good and hop(2*n+1) is bad 3, if both are good channels Tx. Slot=0; Max. Score=0; For(n=0; n<3; n++) if(Score(n)>Max. Score) Tx. Slot=2*n; Max. Score = Score(n); Submission Selecting a pair of slots with the maxim score 12 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Simulation Results • OPNET models for 802. 11 b and BT baseband • Only considered collisions in radio link: – In-band packets that overlap in time result in collision – Collision meant packet loss – Valid assumption for the considered scenario (<3 feet separation) and voice payload’s tolerance for random errors • Two 802. 11 b stations and two BT stations in simulations Submission 13 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 OPNET Scenario Submission 14 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Simulation Results – Key Points • Note changes from first 15 sec (BT silence) to the second 15 sec • Note that the enhanced voice link always outperforms HV 3 and HV 1 links for both BT throughput and 802. 11 b throughput • Note that HV 3 is better than HV 1 for coexistence • Note that the changes in behavior when loads on 802. 11 b networks change (from 5 Mbps ->200 k) Submission 15 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 HV 1 Packet WLAN Load: 5 Mbps Submission 16 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 HV 3 Packets WLAN Load: 5 Mbps Submission 17 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Enhanced Voice Link WLAN Load: 5 Mbps Submission 18 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 BT Master-Slave Throughput WLAN Load: 5 Mbps Submission 19 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 802. 11 b Throughput WLAN Load: 5 Mbps Submission 20 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 BT Master-Slave Throughput WLAN Load: 2 Mbps Submission 21 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 802. 11 b Throughput WLAN Load: 2 Mbps Submission 22 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 BT Master-Slave Throughput WLAN Load: 200 kbps Submission 23 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 802. 11 b Throughput WLAN Load: 200 kbps Submission 24 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Conclusions (1) • Proposals for enhancing voice links for BT: – HV 3 packet as default SCO packet type – Enhanced voice link using new EV 3 packet • Extensive simulation data demonstrates that the proposed methods significantly improve coexistence performance • No changes to the current BT specs, just new usages • Easy implementation through software upgrades Submission 25 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Conclusions (2) Evaluation Questionnaires • Non-Collaborative • Impact on Standards: – New SCO packet type • Regulatory Impact: – None • Complexity: – Software upgrade for most implementations • Interoperability with Non-coexistence Devices: – Drop back to HV 3 packet for non-coexistence devices Submission 26 Jie Liang, Texas Instruments

March 2001 doc. : IEEE 802. 15 -01/026 r 1 Conclusions (3) Evaluation Questionnaires • Classes of Operations: – Both PCF and DCF for 802. 11 b – Voice payload for BT • Voice and Data Support: – Voice • Impact on higher layer: – Mostly none • Impact on Power Management: – None Submission 27 Jie Liang, Texas Instruments